1. Field of the Invention
The present invention relates to a trigger mechanism and functional frame for motion furniture, and more particularly to a safety trigger mechanism for unfolding a drive mechanism of motion furniture and functional frame for motion furniture therewith with higher safety.
2. Description of Related Art
Refer to FIGS. 1-5, a conventional trigger mechanism, for releasing a locked drive mechanism 13 of motion furniture which is shown in FIG. 2 and FIG. 3, mainly includes a fork 3, a pull wire 1, a first restoring spring 4 and a mounting board 2. As shown in FIGS. 3-5, the operating principle of the conventional trigger mechanism is explained as follows: in FIG. 3, since a driving arm 9 cannot turn clockwise in the limit of a limiting rivet 21 mounted on the driving arm 9 after the drive mechanism 13 is mounted, rotating points A, B, C of the driving arm 9 and a push rod 20 of the drive mechanism 13 are designed on one line, and the point A is over the balance point, wherein the balance point is below the point A and the vertical distance between the point A and the balance point is 3-4 mm as experience, and the mechanism is in a locked state under the action of the driving spring 7 because the force produced by the driving spring 7 has an upward component force F1 and the driving arm 9 cannot turn clockwise being stopped by the limiting rivet 21. When it needs to unfold the drive mechanism 13, the conventional trigger mechanism is pulled left by the pull wire 1, in the direction of the pulling force F2 as shown in FIG. 1, so the fork 3 turns anticlockwise about the first rivet 5 (referring to FIG. 1) and its bent edge pushes the upper edge of the driving arm 9 so that the driving arm 9 turns anticlockwise about the square shaft B (as shown in FIG. 4) and overcomes the upward component force F1 from the driving spring 7 until the point A is over the balance point, as shown in FIG. 4 At this time, the push rod 20 of the drive mechanism 13 pushes the connecting rod 8 to turn anticlockwise and the drive mechanism 13 begins to unfold. Finally, the drive mechanism 13 is fully unfolded, as shown in FIG. 5.
However, the conventional trigger mechanism has the shortcomings as follows: the pulling force of the pull wire 1 must be large enough to overcome the upward component force F1 of the driving spring 7, and only when the point A is kept in the balance position, the pulling force is very small or there is almost no pulling force, however, in this situation, the drive mechanism is easy to unfold itself, which will hurt users, especially children.